JP5463463B2 - Ride type ground work vehicle - Google Patents

Description

  In order to perform ground work, left and right wheels that are main drive wheels that are independently driven by two traveling motors, steering wheels that are provided in the front-rear direction with respect to the left and right wheels, and The present invention relates to a riding type ground work vehicle including a driven work machine.

  2. Description of the Related Art Conventionally, a ground work vehicle including a work machine that is driven to perform ground work such as lawn mowing work and tilling is known. Further, in such a ground work vehicle, there is also an electric ground work vehicle including left and right wheels that are main drive wheels that are independently driven by a motor such as an electric motor and a hydraulic motor, and steering wheels such as caster wheels. It is considered.

  For example, there is a lawnmower vehicle equipped with a lawn mower, which is a work machine, and capable of running on its own and driving and operating the lawn mower on the vehicle. be called. An example of a lawn mower is a lawn mowing rotary tool.

  Riding lawn mowers are used exclusively in so-called off-roads such as gardens, and move on the ground for mowing work.

  For example, Patent Document 1 discloses a hybrid power unit equipped with an engine / generator integrated type in which a rotor is connected to an engine shaft of an internal combustion engine. The lawn mower exemplified as a power unit is connected to a plurality of drive wheels with independent electric motors, and each drive wheel can be controlled independently at a variable speed, thereby enabling smooth start and stop of the lawn mower. It is stated that speed change and direction change can be performed. As examples of turning by changing the independent speed of the drive wheels, there are described cases in which an electric motor is connected to each of the left and right rear wheels.

In Patent Document 2, as a hybrid lawn mower, a deck motor for driving a lawn mowing blade, a left and right wheel motor for driving left and right rear wheels that are independently controlled by electric power from an alternator connected to an engine disposed in front, A configuration for driving a steering motor that steers front wheels around an axle in a range of about 180 degrees is disclosed. Here, to turn the lawn mower, the speed difference between the left and right rear wheels is calculated from the input of the steering control unit to control the wheel motor, and the steering signal is given to the steering motor to control the position of the left and right front wheels. . This states that the lawn mower can be turned without steering the left and right rear wheels.
As prior art documents related to the present invention, there are Patent Documents 3 and 4 in addition to Patent Documents 1 and 2.

JP 2006-507789 A US Pat. No. 7,017,327 JP 2005-184911 A Japanese Patent No. 3853907

  In the case of the riding lawn mower vehicle described in Patent Documents 1 and 2, the left and right rear wheels are driven independently by a motor, but when traveling on an inclined surface such as traveling on a contour line across the inclined surface Moreover, it is conceivable that a force in a direction different from the traveling direction acts on each wheel based on the action of gravity. In this case, the steered wheels may not be directed in the direction intended by the driver, or the wheels may slip sideways, making it difficult for the vehicle to travel in the straight direction or the turning direction, which is the direction intended by the driver. There is a possibility. In particular, when the steering wheel is a caster wheel that freely rotates around the vertical axis, it may be more difficult to cause the vehicle to travel in the intended direction.

  In contrast, Patent Document 3 describes a wheel-independent drive electric vehicle in which wheels are independently driven by individual electric motors. In this electric vehicle, the output target value of each electric motor is calculated based on the accelerator pedal depression amount and the vehicle speed, the target yaw rate is obtained from the steering angle and the vehicle speed, and the yaw rate that is the turning angular velocity around the vertical axis passing through the center of gravity of the electric vehicle. The output target value of each electric motor is corrected and output so that the deviation between the detected yaw rate that is the detected value and the target yaw rate is eliminated.

  Patent Document 4 describes a drive control device that gives an output command to each of a plurality of electric motors for driving left and right drive wheels of an electric vehicle. The drive control device includes means for temporarily determining an output command based on an acceleration or deceleration request, and means for correcting a command before being applied to the electric motor from a plurality of state quantities including a detected value of the yaw rate of the vehicle body, This means corrects the torque command so that a positive or negative moment is generated from the lateral acceleration, the detected yaw rate value, or the like according to the sign of the index indicating the yaw movement direction of the vehicle. Further, the vehicle moment is determined based on the difference between the plurality of state amounts fed back and the target state amount obtained using the detected value of the steering angle, and the left and right drive wheels are determined according to the determined vehicle moment. Distributing torque.

In the case of such a configuration described in Patent Documents 3 and 4, an electric vehicle that is not a riding lawnmower vehicle, but when the vehicle travels on an inclined surface, a straight traveling direction or a turning direction that is intended by the driver There is a possibility of driving to. However, with these configurations, it is difficult to set independent correction values for the left and right drive wheels, and control is performed to correct the rotational speed command of the electric motor based on the deviation between the detected value of the yaw rate and the target value. It is difficult to freely set the behavioral characteristics of the vehicle during operation, that is, the vehicle speed and the like. For example, in the configuration of Patent Document 3, the same output target is calculated by each electric motor for driving left and right wheels, and the output target is corrected based on the deviation regarding the yaw rate, but a specific correction method is not described. . Further, in the configuration of Patent Document 4, the same output command is tentatively determined in each electric motor and the torque command is corrected from the yaw rate detection value or the like. However, the yaw rate target value is not obtained, but the yaw rate detection value is determined. It is difficult to freely set the behavior characteristics of the vehicle during the control action based on the deviation between the target value and the target value.
Such inconvenience may also occur in the case of a riding-type ground working vehicle having another working machine in addition to the riding-type lawn mowing vehicle having the above-described lawn mower.

  The object of the present invention is to enable traveling in the direction intended by the driver even when the vehicle is traveling on an inclined surface in a configuration in which the left and right wheels are independently driven by a motor in the riding type ground work vehicle, Furthermore, it is to make it easy to freely set the behavior characteristic of the vehicle at the time of control action based on the deviation between the detected value of the yaw rate and the target value.

A riding type ground work vehicle according to the present invention is provided with left and right wheels, which are main drive wheels that are independently driven by a left wheel travel motor and a right wheel travel motor, and separated in the front-rear direction with respect to the left and right wheels. A steering-type ground working vehicle including a steering wheel and a work machine driven to perform ground work, wherein an acceleration instruction of an acceleration operator and a turning instruction of a turning operator input by a driver are provided . Command value calculation means for calculating target rotation speed command values for left and right wheels of the left and right wheel travel motors from the detection signal , yaw rate detection means for detecting the yaw rate of the vehicle, and acceleration instruction and the target yaw rate calculation means for calculating a target yaw rate based on the turn instruction, based on a deviation between the target yaw rate and the yaw rate detection value, the traveling motor Niso for left wheel and right wheel A correction coefficient obtaining means for obtaining a correction coefficient for the left wheel and the right wheel to respective relationships, the correction coefficient for the left wheel and right wheel of the respective target rotational speed command value for the left wheel and the right wheel Control means for controlling the driving of the driving motor for the left wheel and the right wheel based on the corrected target rotational speed command values for the left wheel and the right wheel after correction, and the shaft provided in the turning operator A fixed portion that is rotatably supported and fixed to the vehicle body, a swing arm that is fixed to the shaft portion and swings as the shaft portion rotates, and between the swing arm and the fixed portion of the shaft portion It is provided between the loosely-fitted loosely-fitting arm and the swingable arm and the loosely-fitted arm, and the swingable arm is allowed to play only when the swinging amount from the neutral position of the swinging arm is equal to or greater than a predetermined amount. Abut the fitting arm and swing the loose fitting arm in the same direction as the swing arm A first spring that is provided between the contact mechanism and the swing arm and the loosely fitted arm, and biases the swinging arm with a biasing force that increases as the swing amount of the swingable arm with respect to the loosely fitted arm increases. And a second spring that is provided between the loose-fitting arm and the fixing part and that urges the loose-fitting arm with a second urging force that increases as the swing amount of the loose-fitting arm with respect to the fixing part increases. It is characterized by that . In the above configuration according to the present invention, the traveling motor may be a hydraulic motor or the like in addition to the electric motor.

According to the riding type ground work vehicle according to the present invention, in the configuration in which the left and right wheels can be independently driven by the motor, even when the vehicle is traveling on an inclined surface, it is possible to travel in the direction intended by the driver, Furthermore, it is possible to easily set the behavioral characteristics of the vehicle during the control action based on the deviation between the detected value of the yaw rate and the target value. In addition, the operation force necessary to operate the turning operation element is increased as the operation amount from the neutral position is increased without using complicated control, and with respect to an increase in the operation amount with a certain operation amount as a boundary. The degree of increase in operating force can be increased.

Further, in the riding-type ground working vehicle according to the present invention, preferably, the travel motors for the left wheel and the right wheel are respectively the electric motor, further, the rotational speed of the traveling motor for the left wheel and the right wheel Rotation speed detection means for the left wheel and right wheel to be detected are provided, and the control means is a target rotation speed command value for the left wheel and right wheel after correction by the correction coefficient , and for the left wheel and right wheel. The torque command value of each traveling motor is calculated based on the deviation from the detected rotational speed value of the traveling motor, and the driving of the traveling motor for the left wheel and the right wheel is controlled by each torque command value.

According to the said structure, the drive of two traveling motors can be controlled more accurately.

In the riding-type ground work vehicle according to the present invention, preferably, the left wheel and right wheel travel motors are hydraulic motors, respectively , and at least two for the left wheel and right wheel travel motors. One or two actuators that can discharge pressure oil independently from each of the two outlets and can change the discharge amount of the pressure oil discharged from the two outlets , and driving for the left wheel and the right wheel and a rotation speed detecting means for the left wheel and the right wheel to detect the rotation speed of the motor, the control means includes a target rotational speed command value for the left wheel and right wheel after the correction by the correction coefficient, the left Based on the deviation from the rotational speed detection value of the driving motor for the wheel and the right wheel, by changing the discharge amount of the pressure oil discharged from the two discharge ports , the driving motor for the left wheel and the right wheel Control drive That.

Further, in the riding-type ground working vehicle according to the present invention preferably comprises an actuator power source that drives the actuator, one or two actuators, operatively connected with two control axes, the two control axes It is, and a two control axis motor for changing the rotation angle of the two control axes, by the rotation angle of the two control shafts change, discharged from the two discharge ports corresponding to each of the two control shafts The pressure oil discharge amount of the actuator changes, and the control means includes a target rotational speed command value for the left wheel and the right wheel after correction by a correction coefficient , and a driving motor for the left wheel and the right wheel. by the based on the deviation between the rotational speed detection value to calculate the rotation angle command values for the two control axes, and controls the drive of the two control shaft motors by the respective rotation angle command value Controlling the driving of the travel motor for the left wheel and the right wheel.

According to the said structure, the drive of two traveling motors can be controlled more accurately.

In the riding-type ground work vehicle according to the present invention, preferably, the correction coefficient acquisition means includes a calculation unit that performs a calculation including a PI calculation based on a deviation between the target yaw rate and the yaw rate detection value, and an output of the calculation unit. A main correction coefficient acquisition unit that acquires correction coefficients for the left wheel and the right wheel corresponding to the target rotational speed command values for the left wheel and the right wheel. Among the correction factors for the left wheel and right wheel when increasing, one correction factor is set to a constant value, and when the other correction factor is decreased or increased, the output of the calculation unit decreases . Among the correction coefficients for the right wheel and the right wheel , the other correction coefficient is set to a constant value, and one correction coefficient is decreased or increased.

  According to the above configuration, it becomes easy to set the behavior characteristics of the vehicle during the control action based on the yaw rate detection value.

In the riding-type ground work vehicle according to the present invention, preferably, the correction coefficient acquisition means includes a calculation unit that performs a calculation including a PI calculation based on a deviation between the target yaw rate and the yaw rate detection value, and an output of the calculation unit. A main correction coefficient acquisition unit that acquires correction coefficients for the left wheel and the right wheel corresponding to the target rotational speed command values for the left wheel and the right wheel. among the correction coefficients for the left wheel and right wheel in the case of increasing, as well as one of the correction coefficient and a constant value of a positive value, the left when decreasing the other correction coefficient, the output of the arithmetic unit is reduced Of the correction coefficients for wheels and right wheels , the other correction coefficient is set to a constant positive value, one correction coefficient is decreased, and the absolute value of the output of the arithmetic unit becomes a predetermined value or more. run for the left wheel and the right wheel in the case Of the motor, so as to generate the drive torque in the reverse direction to the normal rotation corresponding to the traveling direction in one travel motor, it is changed to the negative correction coefficient corresponding to one traction motor from positive.

According to the above configuration, appended direction of torque for reverse rotation with respect to the normal rotation of the absolute value of the output of the arithmetic unit corresponding to the traveling direction on one side of the running motor of the two travel motors when equal to or greater than a predetermined value Therefore, even when the deviation between the target yaw rate and the detected yaw rate is large, the deviation can be eliminated more quickly and stable running can be easily realized.

In the riding type ground work vehicle according to the present invention, preferably, the acceleration operator is a pedal that can input an acceleration instruction , and the turning operator is a steering wheel that can input a turning instruction .

In the riding type ground work vehicle according to the present invention, preferably, the steering wheel is operatively connected to a caster wheel or a turning operation element , and is mechanically steerable in conjunction with an operation of the turning operation element. This is a steering wheel.

  According to the riding type ground work vehicle according to the present invention, in the configuration in which the left and right wheels can be independently driven by the motor, even when the vehicle is traveling on an inclined surface, it is possible to travel in the direction intended by the driver, Furthermore, it is possible to easily set the behavioral characteristics of the vehicle during the control action based on the deviation between the detected value of the yaw rate and the target value.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which looked at the structure of the lawn mower vehicle which is the riding type ground work vehicle of 1st Embodiment which concerns on this invention from the upper direction. It is a figure which shows the structure of the lawnmower vehicle of 1st and 2nd embodiment. It is a block diagram which shows the function structure of the controller which comprises the control system of the lawnmower vehicle of 1st Embodiment. In the lawnmower vehicle of a 1st embodiment, it is a schematic diagram showing a situation in the case of straight running. In the lawnmower vehicle of 1st Embodiment, it is the schematic which shows the mode in the case of turning driving | running | working. It is a figure which shows the map showing the relationship between a steering angle and a steering coefficient used in the steering characteristic acquisition part shown in FIG. It is a figure which shows the map showing the relationship between a PID output and a yaw control coefficient used in the main correction coefficient acquisition part shown in FIG. In FIG. 6, it is a figure for demonstrating the change of a yaw control coefficient when a PID output changes. It is a figure which shows the 1st example of another example of the map shown in FIG. It is a figure which shows the 2nd example of another example of the map shown in FIG. It is the schematic which looked at the structure of the lawn mower vehicle which is the riding type ground work vehicle of 2nd Embodiment which concerns on this invention from the upper direction. It is a block diagram which shows the function structure of the controller in the lawnmower vehicle of 2nd Embodiment. It is the schematic which looked at the structure of the lawn mower vehicle which is the riding type ground work vehicle of 3rd Embodiment which concerns on this invention from the upper direction. It is a figure which shows the structure of the lawn mower vehicle of 3rd and 4th embodiment. It is a block diagram which shows the function structure of the controller of the lawnmower vehicle of 3rd Embodiment. It is the schematic which looked at the structure of the lawn mower vehicle which is the riding type ground work vehicle of 4th Embodiment which concerns on this invention from the upper direction. It is the schematic which looked at the vehicle of FIG. 16 in the horizontal direction. It is a block diagram which shows the function structure of the controller in the lawnmower vehicle of 4th Embodiment. It is a perspective view which shows the lawnmower vehicle which is the riding type ground work vehicle of 5th Embodiment which concerns on this invention. It is a perspective view which shows the rotation support structure of the steering operator provided in the lawnmower vehicle of 5th Embodiment. It is an enlarged view which shows a mode that the AA part of FIG. 20 was cut | disconnected and the upper spring and the lower spring were removed. It is the figure which cut | disconnected a part of FIG. 21 which looked at the state which rotates a steering operator from the neutral position to one side in time series, and was seen from the upper direction to the downward direction. In 5th Embodiment, when rotating a steering operator, it is a figure which shows the relationship between steering operating force and a steering angle which shows that the increase degree of steering operating force changes with a predetermined steering angle threshold value as a boundary. is there.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, a description will be given of a case where the riding type ground working vehicle is a lawnmower vehicle including a lawn mower as a working machine. However, the riding type ground working vehicle according to the present invention is not limited to this, for example, the ground As a vehicle for performing a work on the ground, that is, a ground work, a vehicle having a tiller, a vehicle having a seedling planting machine, a vehicle having a ground leveling machine, a vehicle having a digging machine, and the like may be used.

  1 to 10 show a first embodiment of the present invention. In FIG. 2, lever sensors 98 and 100 which are components of a second embodiment to be described later are also shown in parentheses. As shown in FIG. 1, a lawnmower vehicle 10 that is a riding-type ground working vehicle is a self-propelled off-road vehicle suitable for lawn mowing, and is a front-rear direction of a main frame 12 that is a vehicle body (left-right direction in FIG. 1). Two left and right caster wheels 14 and 16 and two left and right wheels 18 and 20 are supported and provided at positions separated from each other. The left and right caster wheels 14 and 16 are front wheels and steered wheels. The two left and right wheels 18 and 20 are rear wheels and are main drive wheels. Each of the left and right wheels 18 and 20 is an electric motor for left and right wheels which is two left and right traveling motors provided so as to be connected to each of the left and right wheels 18 and 20 via a power transmission unit including a reduction mechanism (not shown). 22 and 24 are independently driven to travel. By making the rotational speeds of the left and right wheels 18 and 20 coincide with each other by the left and right wheel electric motors 22 and 24, the vehicle can travel straight, and by generating a difference in rotational speed between the left and right wheels 18 and 20, turning the vehicle Enables traveling. Thus, in the present embodiment, the wheel electric motors 22 and 24 are used as the drive source of the lawnmower vehicle 10. The speed reduction mechanism provided in the power transmission unit uses, for example, a one-stage or multiple-stage reduction gear device. In FIG. 1, wheel electric motors 22 and 24 and a speed reduction mechanism (not shown) are provided in housings 30 constituting power generation units 26 and 28 provided on the left and right wheels 18 and 20, respectively. Each housing 30 is supported by the main frame 12. In addition, you may employ | adopt the structure which transmits the motive power of the electric motors 22 and 24 for wheels to the right-and-left wheels 18 and 20 without decelerating without using a deceleration mechanism. Further, the caster wheels 14 and 16 are capable of free steering of 360 degrees or more around the axis in the vertical direction (front and back direction in FIG. 1).

  Further, the lawnmower vehicle 10 supports a lawn mower (more) 32 as a work machine on the lower side in the middle part of the main frame 12 in the front-rear direction. As shown in FIG. 17 used in an embodiment described later, the lawn mower 32 is provided with a lawn mowing blade 36 that is a lawn mowing rotary tool inside a mower deck 34. The lawn mowing blade 36 has a rotation axis oriented in the vertical direction (vertical direction in FIG. 17), and a plurality of blades are arranged around the rotation axis. Make it possible.

  Moreover, as shown with reference to FIG. 17, the lawnmower vehicle 10 is of a so-called hybrid type including an engine 38, a generator 40, and a battery 42 (FIG. 2). The power of the engine 38 is used to generate power from the generator 40, and the generated power is a power supply unit and can be supplied to the battery 42, which is a secondary battery. For this reason, the engine 38 and the generator 40 are used as a power supply source to the battery 42. However, the lawnmower vehicle 10 does not include the engine 38 and the generator 40, and the battery 42 may be supplied with charging power from the outside. In addition, as a power supply unit, a battery having a self-power generation function such as a fuel cell or a solar cell can be used together with a battery that is supplied with charging power from the outside. In addition, another power storage unit such as a capacitor can be used instead of the battery 42.

  As shown in FIG. 17, the power of the output shaft of the engine 38 can be transmitted to the rotating shaft of the lawn mowing blade 36 via a power transmission mechanism 44 including a pulley belt mechanism and a universal joint mechanism. Further, an electromagnetic clutch mechanism (not shown) is provided in the power transmission mechanism 44, and the connection / disconnection of the electromagnetic clutch can be changed by turning on or off a mower switch (not shown) provided near the seat 46. In this case, a signal indicating ON / OFF of the mower switch is transmitted to the controller 48 (FIG. 1) provided in the lawnmower vehicle 10, and the controller 48 controls connection / disconnection of the electromagnetic clutch based on this signal. The power transmission mechanism 44 can be provided with a clutch mechanism that can be manually engaged and disengaged instead of the electromagnetic clutch mechanism.

  Further, when the lawn mowing vehicle 10 does not include the engine 38 and the generator 40 and the battery 42 is configured to receive charging power from the outside, the lawn mowing blade 36 (see FIG. 17) is used. An electric motor for mower (not shown) can be operatively connected to the rotating shaft so that power can be transmitted. In this case, when a signal indicating ON or OFF of the mower switch provided near the seat 46 (see FIG. 17) is input to the controller 48 (FIG. 1), the controller 48 determines the mower electric motor based on this signal. Control the operating state. Further, a mower hydraulic motor may be used instead of the mower electric motor. Thus, the lawn mower 32 is driven to perform ground work.

  Further, a grass collection tank (not shown) can be mounted on the lawn mowing vehicle 10, and the grass collection tank and the end of the mower deck 34 (see FIG. 17) can be connected by a duct, and a grass collection fan can be provided inside the duct. . According to this configuration, the grass cut by the lawn mowing blade 36 can be collected in the grass collecting tank through the duct by driving the grass collecting fan.

  Returning to FIG. 1, the wheel electric motors 22, 24 have a function of outputting a rotational driving force to the wheels 18, 20 when electric power is supplied, but are regenerated when braking is applied to the wheels. You may give the function as a generator which collect | recovers energy. The wheel electric motors 22 and 24 are, for example, three-phase synchronous electric motors or induction electric motors.

  In addition to the lawn mowing blade type, as a lawn mowing rotary tool that is a lawn mower, a lawn mowing reel is arranged such that, for example, a spiral blade is placed on a cylinder having a rotation axis parallel to the ground surface, and the lawn is sandwiched and mowed. A mold can also be used.

  In addition, the caster wheels 14 and 16 other than two, for example, only one can also be provided in the lawnmower vehicle 10, and three or more can also be provided. In the present embodiment, the left and right wheels 18 and 20 that are main driving wheels are used as rear wheels, and the caster wheels 14 and 16 are used as front wheels, but the left and right wheels 18 and 20 that are main driving wheels are used as front wheels. 14 and 16 can be rear wheels.

  The left and right caster wheels 14 and 16 are operably attached at the same position in the front-rear direction (left-right direction in FIG. 1) on the bottom surface side of the front end (left end in FIG. 1) of the main frame 12. Further, a seat 46 (see FIG. 17) is provided on the upper surface side of the intermediate portion in the left-right direction (vertical direction in FIG. 1) in the middle portion in the front-rear direction of the main frame 12. In the present specification, the front side refers to the front side of the vehicle on the left side of FIG. 1, and the rear side refers to the rear side of the vehicle on the right side of FIG. Further, the left and right wheels 18 and 20 are rotatably supported on the bottom surface side of the position between the seat 46 and the rear end, which is the same position in the front-rear direction of the main frame 12. The lawn mower 32 is disposed between the left and right caster wheels 14 and 16 and the left and right wheels 18 and 20 on the bottom surface side of the main frame 12. As the main frame 12, a metal material such as a steel material can be used and formed into a beam structure or the like.

  The controller 48 comprehensively controls the operation of the wheel electric motors 22 and 24. Since the controller 48 is an electric circuit, it can be distributed at a plurality of locations. In FIG. 1, one controller 48 is shown. For example, the controller 48 can be centrally arranged at a position below the seat 46 (see FIG. 17) on the upper surface side of the main frame 12. When the controllers 48 are arranged in a distributed manner, the controllers 48 are connected to each other by a signal cable or the like. The controller 48 includes a driver circuit such as an inverter circuit for driving the electric motors 22 and 24 and a control circuit unit such as a CPU and a memory.

  On the upper surface side of the main frame 12, in addition to the seat 46, a steering operator 50, a forward accelerator pedal 52, a reverse accelerator pedal 54, and a brake pedal (not shown) are provided. The steering operator 50 receives a steering angle, which is a steering angle, as a turning instruction input. The steering operator 50 detects the steering angle by the steering angle sensor 56 and outputs the detected signal to the controller 48. A monolever type structure can also be used as the turning operation element. The forward accelerator pedal 52 is an acceleration operator for instructing acceleration in the forward direction, and the reverse accelerator pedal 54 is an acceleration operator for instructing acceleration in the reverse direction. Thus, each accelerator pedal 52 and 54 can input an acceleration instruction.

  The steering operation element 50 is a turning operation element for instructing turning, and is, for example, a steering wheel having a circular shape or a non-circular shape, and adjusts the turning direction of the left and right wheels 18 and 20 by rotating or swinging. It has a function. As in the illustrated example, when the steering operator 50 is a steering wheel, the steering operator 50 can be rotated at an arbitrary angle in the clockwise direction (right rotation direction) or the counterclockwise direction (left rotation direction) around its rotation axis. Further, the operation amount of the steering operator 50, that is, the steering angle, is detected by the steering angle sensor 56 as a turning instruction input by the driver, and a signal from the steering angle sensor 56 is a controller 48 shown in FIGS. And the operation of the wheel electric motors 22 and 24 is controlled. In this way, the steering operator 50 can input a turning instruction. As the steering angle sensor 56, a potentiometer, an electrical sensor such as an encoder, an optical sensor, or the like can be used. In the following description, “steering angle” represents the steering direction by the sign of the value.

  The accelerator pedals 52 and 54 are provided separately for the forward side and the backward side, but the forward side and the backward side can be combined with one accelerator pedal. For example, a structure that swings and supports an accelerator pedal on a fixed horizontal shaft and that can be stepped on the front side and the rear side, instructing forward by stepping on the front, and instructing backward by stepping on the rear It can also be. Each accelerator pedal 52, 54 can be depressed with an arbitrary depression amount. The amount of depression of each accelerator pedal 52, 54 is detected by an accelerator depression sensor 58 as an acceleration instruction input by the driver, and a signal from the accelerator depression sensor 58 is transmitted to the controller 48 shown in FIGS. The operation of the wheel electric motors 22 and 24 connected to the left and right wheels 18 and 20 is controlled. As each accelerator depression sensor 58, an electrical sensor such as a potentiometer or an encoder can be used. The accelerator pedal having forward and reverse functions is constituted by a single accelerator pedal, and a switch or button for selecting either forward or reverse is provided, depending on the operation state of this switch or button. Thus, it is possible to switch whether one accelerator pedal functions for forward movement or reverse movement.

  Such a lawnmower vehicle 10 can accelerate the vehicle forward or backward by depressing the accelerator pedals 52 and 54. Further, when the accelerator pedals 52 and 54 are operated or not operated, the vehicle can be turned according to the steering direction of the steering operator 50 by steering the steering operator 50. For example, when the forward accelerator pedal 52 is depressed with the steering operator 50 in the neutral position for instructing a straight traveling state, the wheels 18 and 20 are rotated forward. The larger the amount of depression, the higher the number of rotations of the wheels 18 and 20. , The forward speed increases. Instead, when the reverse accelerator pedal 54 is depressed, the wheels 18 and 20 are rotated backward, and the larger the amount of depression, the higher the number of rotations of the wheels 18 and 20 and the higher the reverse speed. Thereby, the lawnmower vehicle 10 can be moved forward or backward at an arbitrary speed.

  Further, when the steering operator 50 is rotated clockwise, that is, to the right while the forward accelerator pedal 52 is in an appropriate depression amount, the rotational speed of the left wheel 18 becomes higher than the rotational speed of the right wheel 20, The lawnmower vehicle 10 can be turned to the right while traveling. When the rotation angle from the neutral position of the steering operator 50 is increased, the difference between the rotation speed of the left wheel 18 and the rotation speed of the right wheel 20 increases, and conversely, the rotation angle from the neutral position of the steering operator 50 is decreased. Thus, the difference in rotational speed between the left and right wheels 18 and 20 can be reduced. Thereby, a turning radius can be adjusted. When the steering operator 50 is rotated counterclockwise, that is, to the left, the rotational speed of the right wheel 20 becomes higher than the rotational speed of the left wheel 18, and the lawnmower vehicle 10 can be turned left while traveling.

  Moreover, it is also possible to turn the vehicle while changing the traveling speed by changing the amount of depression of the forward accelerator pedal 52. By depressing the reverse side accelerator pedal 54 and operating the steering operator 50, it is possible to make a turn during reverse.

  Further, in the case of the present embodiment, the vehicle can be caused to travel in the direction intended by the driver regardless of traveling on the inclined surface of the lawnmower vehicle 10. For this reason, the lawnmower vehicle 10 is provided with a yaw rate sensor 60 which is a yaw rate detecting means for detecting a yaw rate that is a turning angular velocity around a vertical axis passing through the center of gravity of the vehicle. A detection signal of the yaw rate sensor 60 is transmitted to the controller 48. In addition, the wheel electric motors 22 and 24 feed back signals representing the rotation speed, rotation direction, rotation angle, current value, and the like to the controller 48 using various sensors. For example, each electric motor 22, 24 is provided with a rotation speed sensor 62 that is a rotation speed detection means, and a detection signal of the rotation speed sensor 62 is input to a motor control means 64 (FIG. 2), which will be described later, constituting the controller 48. doing. Each electric motor 22, 24 is provided with a rotation angle sensor instead of the rotation speed sensor 62, and a detection signal of the rotation angle sensor is input to the rotation speed calculation means constituting the controller 48, and each electric motor is determined from the rotation angle detection value. The rotational speeds 22 and 24 can also be calculated. In this case, the rotation angle sensor and the rotation speed calculation means constitute a rotation speed detection means.

  Further, the controller 48 independently controls the output torques of the left and right wheel electric motors 22 and 24 using the detection signals of these various sensors. For this purpose, torque command values for the left and right wheel electric motors 22 and 24 for driving the left and right wheels 18 and 20 are calculated, and outputs corresponding to the respective torque command values are generated. Based on these outputs, an inverter circuit or the like is generated. The drive signal for the driver circuit is generated. Thereby, the voltage corresponding to these torque command values is supplied to the corresponding wheel electric motors 22 and 24 using the voltage of the power supply unit, and the output torque of the wheel electric motors 22 and 24 can be controlled. Next, the configuration and function of the controller 48 will be described in detail with reference to FIGS. As shown in FIG. 2, the controller 48 includes a storage unit 66, and a lawnmower vehicle control program is stored in the storage unit 66.

  First, prior to the description of FIGS. 2 and 3, the straight traveling and the turning traveling of the lawnmower vehicle 10 will be described with reference to FIGS. 4 and 5. Below, it demonstrates using the code | symbol of FIG. In these figures, the state in the top view of the caster wheels 14 and 16 and the wheels 18 and 20 in the lawnmower vehicle 10 is schematically shown. Here, the left and right wheels 18 and 20 are driven and driven independently.

  FIG. 4 shows a case of straight running, in which the steering operator 50 is maintained in a neutral state and the forward accelerator pedal 52 is depressed, and all of the caster wheels 14 and 16 and the wheels 18 and 20 are ground speeds in the same direction. At the same speed. FIG. 5 shows a case of turning, where (a) shows the case where the turning center position O1 is outside the wheels 18 and 20 on the extension of the wheels 18 and 20 in the axle direction, and (b) Each of the cases where the turning center position O2 is referred to as a belief turning in which the wheel 18 or 20 is in the ground contact position is shown. (C) is that the turning center position O3 is exactly the center position between the wheels 18 and 20 on the axles of the wheels 18 and 20, and the absolute values of the speeds of the wheels 18 and 20 are the same. The case where the speed direction of the one-side wheel 18 and the speed direction of the other-side wheel 20 are opposite to each other is referred to as super-trust turning, spin turning, or zero turn. In this case, the lawnmower vehicle 10 turns around the turning center position O3.

  In addition, (a) to (c) in FIG. 5 shows one example of the turning travel, and the turning between the cases of these examples may be performed. For example, the turning center position may be inside the left and right wheels 18 and 20, but may be biased toward one of the wheels instead of the center position between the left and right wheels 18 and 20. These turning travels are realized by adjusting the rotation direction and the rotation speed of the wheel electric motors 22 and 24 corresponding to the left and right wheels 18 and 20, respectively.

Next, the configuration of the controller 48 and the functions thereof will be described with reference to FIGS. In the description of FIG. 3, the same elements as those of FIG. As shown in FIG. 2, the controller 48 includes a command value calculation unit 68, a target yaw rate calculation unit 70, a correction coefficient acquisition unit 72, and a control unit 74. The command value calculation means 68 uses the accelerator depression sensor 58 and the steering angle sensor 56 to generate two wheel electric motors based on the acceleration instruction and the turning instruction input by the driver, that is, the accelerator depression amount and the steering angle. Two target rotational speed command values of 22 and 24 are calculated. As shown in FIG. 3, the command value calculation means 68 obtains a temporary target rotational speed command value Vr ^* common to the two wheel electric motors 22 and 24 corresponding to the accelerator depression amount. For this purpose, for example, map data representing the relationship between the accelerator depression amount and the temporary target rotational speed command value Vr ^* is stored in the storage unit 66 (FIG. 2), and the map data is obtained from the detected accelerator depression amount. The provisional target rotational speed command value Vr ^* is acquired by referring to it. In this case, the temporary target rotational speed command value Vr ^* may be calculated simply using the relational expression representing the relationship between the accelerator depression amount and the temporary target rotational speed command value Vr ^* and the detected accelerator depression amount. it can.

  The command value calculation means 68 includes a steering characteristic acquisition unit 76, and the steering characteristic acquisition unit 76 corresponds to the steering angle of the steering operator 50 and the steering coefficient corresponding to each of the left and right wheel electric motors 22 and 24. Vkl and Vkr are obtained. The steering coefficients Vkl and Vkr are ratios (= V2 / V1) of the target rotational speed V2 corresponding to the steering angle with respect to the maximum rotational speed V1 in each of the electric motors 22 and 24, which is the target rotational speed with respect to the maximum rotational speed. It can be rephrased as a ratio. For example, map data representing the relationship between the steering angle and the steering coefficient is stored as the steering characteristic in the storage unit 66 (FIG. 2). FIG. 6 shows an example of this map.

In FIG. 6, the steering angle is represented by the horizontal axis, and the steering operator 50 is greatly rotated to the right, that is, clockwise as it goes to the right, and the steering operator 50 is moved to the left, that is, toward the left. This represents a large rotation in the counterclockwise direction. The steering angle shown in FIG. 6 is positive when going to the right side and negative when going to the left side. The vertical axis in FIG. 6 represents the steering coefficients Vkl and Vkr. In FIG. 6, a solid line Vkl represents the relationship between the steering coefficient for the left wheel multiplied by the temporary target rotational speed command value Vr ^* of the left wheel electric motor 22 and the steering angle. A broken line Vkr in FIG. 6 represents the relationship between the steering coefficient for the right wheel multiplied by the temporary target rotational speed command value Vr ^* of the right wheel electric motor 24 and the steering angle.

  In the example of FIG. 6, when the steering operator 50 is rotated to the right from the neutral position, the left wheel steering coefficient Vkl is kept constant, but the right wheel steering coefficient Vkr gradually decreases linearly. Further, when the steering angle becomes larger than a certain threshold value (80 degrees in FIG. 6), the right wheel steering coefficient Vkr becomes a negative value and becomes smaller. On the other hand, when the steering operator 50 is rotated to the left from the neutral position, the right wheel steering coefficient Vkr is kept constant, but the left wheel steering coefficient Vkl gradually decreases linearly. Further, when the steering angle becomes smaller than a certain threshold value (−80 degrees in FIG. 6), the left wheel steering coefficient Vkl becomes a negative value and becomes smaller. In the example of FIG. 6, the inclination with respect to the steering angle when the steering coefficients Vkr and Vkl decrease differs depending on whether the steering coefficients Vkr and Vkl are positive or negative. And the negative slope can be set to the same slope. In this case, in each of the steering coefficients Vkr and Vkl, a straight line indicating that the steering characteristics Vkr and Vkl decrease as the absolute value of the steering angle increases becomes a single straight line.

2 and 3, the command value calculation means 68 uses the steering characteristics Vkr and Vkl acquired in this way as the temporary target rotational speed command values Vr of the left wheel electric motor 22 and the right wheel electric motor 24. ^* the multiplied respectively with the target rotational speed command value for the target rotational speed command values Vrl ^* and the right wheel 20 for the left wheel 18 Vrr ^*, it is calculated. For example, when the steering operator 50 is in the neutral position and the steering angle is 0 in FIG. 6, 1 is set as the steering coefficients Vkr and Vkl, and therefore the target rotational speed command value Vrl ^* for the left wheel 18 and The target rotational speed command value Vrr ^* for the right wheel 20 remains the same temporary target rotational speed command value Vr ^* . This corresponds to the straight traveling of FIG.

In contrast, when the steering angle is reduced in FIG. 6, that is, when the steering operator 50 is rotated to the left, only the left wheel steering coefficient Vkl becomes smaller than 1, so the target rotational speed of the left wheel electric motor 22 is reduced. Only the command value Vrl ^* is smaller than the temporary target rotational speed command value Vr ^* , which corresponds to turning the vehicle in FIG. 5A to the left. As the turning angle of the steering operator 50 to the left is increased, that is, as the absolute value of the steering angle is increased, the steering coefficient Vkl for the left wheel is greatly reduced, so that the turning radius when the vehicle turns left is reduced. It becomes a trend. Further, when the left wheel steering coefficient Vkl further decreases to zero, the driving torque generated by the left wheel electric motor 22 becomes zero. In this case, if the rotational speed of the left wheel electric motor 22 is actually 0, this corresponds to the case of the belief turning shown in FIG. Further, when the left wheel steering coefficient Vkl further decreases and becomes a negative value during forward movement, the target rotational speed command value Vrl ^* of the left wheel electric motor 22 also becomes a negative value, which is the left wheel electric motor 22. Corresponds to generating torque in the reverse direction. In this case, if the left wheel steering coefficient Vkl is −1, the rotational speed of the right wheel electric motor 24 and the rotational speed of the left wheel electric motor 22 are actually opposite in magnitude. Are the same, it corresponds to the case of super-revolution in FIG. In the above description, the case of turning left has been described, but the case of turning right is the same except that the left and right are reversed.

Meanwhile, the target yaw rate calculating section 70, the calculated target rotational speed command values Vrl ^*, from Vrr ^*, calculates the target yaw rate gamma ^*. That is, the target yaw rate calculation means 70 calculates the target yaw rate γ ^* based on the accelerator depression amount and the steering angle acquired by the accelerator depression sensor 58 and the steering angle sensor 56. That is, the target rotational speed command value Vrl for the left and right wheels 18 and 20 ^*, and Vrr ^*, a speed reduction ratio by the reduction mechanism, and a radius of the left and right wheels 18 and 20 of the vehicle is a ground average speed of the left and right wheels 18 and 20 The average speed and the ground speed difference between the left and right wheels 18 and 20 are obtained. Also, from the vehicle specifications such as the average speed of the vehicle, the ground speed difference between the left and right wheels 18 and 20, and the longitudinal length between the axles of the left and right wheels 18 and 20 and the ground contact positions of the left and right caster wheels 14 and 16. A target yaw rate γ ^* is calculated. In this embodiment, when the vehicle is viewed from above, the yaw rate in the counterclockwise direction around the vertical axis passing through the center of gravity of the vehicle is positive, and the reverse yaw rate is negative. .

Further, the correction coefficient acquisition means 72 performs two corrections related to the two wheel electric motors 22 and 24 based on the deviation between the target yaw rate γ ^* and the yaw rate detection value γ detected by the yaw rate sensor 60. Get the coefficient. For this purpose, the correction coefficient acquisition unit 72 includes a PID calculation unit 78 that performs PID calculation including PI calculation, and a main correction coefficient acquisition unit 80. The PID calculation unit 78 receives a deviation between the target yaw rate γ ^* and the yaw rate detection value γ detected by the yaw rate sensor 60, performs PID calculation, and outputs the PID output obtained by the calculation to the main correction coefficient acquisition unit 80. input. The main correction coefficient acquiring section 80, second target rotational speed command values for the left and right wheels 18 and 20 from the PID output Vrl ^*, corresponding to Vrr ^*, the yaw control coefficient is a correction coefficient for the left and right wheels 18 and 20 of the 2 Obtain and output Kl and Kr. The yaw control coefficients Kl and Kr are ratios (= V2 ′ / V1 ′) of the target rotational speed V2 ′ corresponding to the PID output with respect to the maximum rotational speed V1 ′ of the electric motors 22 and 24, and this is the maximum rotational speed. In other words, the ratio of the target rotational speed to For this purpose, for example, map data representing the relationship between the PID output and the yaw control coefficients Kl and Kr is stored in the storage unit 66 (FIG. 2) as the yaw control characteristic. FIG. 7 shows an example of this map.

In FIG. 7, the PID output is represented by the horizontal axis, indicating that the PID output increases toward the right, and the PID output decreases toward the left. The vertical axis in FIG. 7 represents the yaw control coefficients Kl and Kr. In FIG. 6, the solid line Kl represents the relationship between the left wheel yaw control coefficient multiplied by the target rotational speed command value Vrl ^* of the left wheel electric motor 22 and the PID output. A broken line Kr in FIG. 7 represents the relationship between the right wheel yaw control coefficient multiplied by the target rotational speed command value Vrr ^* of the right wheel electric motor 24 and the PID output.

  In the example of FIG. 7, when the PID output becomes larger than 0, the right wheel yaw control coefficient Kr is maintained at a constant positive value, but the left wheel yaw control coefficient Kl gradually decreases linearly. . Further, when the PID output becomes larger than a certain threshold value (0.5 in FIG. 6), the left wheel yaw control coefficient Kl becomes a negative value and becomes smaller. On the other hand, when the PID output is smaller than 0, the left wheel yaw control coefficient Kl is maintained at a constant positive value, but the right wheel yaw control coefficient Kr gradually decreases linearly. Further, when the PID output becomes smaller than a certain threshold value (−0.5 degrees in FIG. 6), the right wheel yaw control coefficient Kr becomes a negative value and becomes smaller. That is, when the PID output of the PID calculation unit 78 increases, the main correction coefficient acquisition unit 80 sets one of the two yaw control coefficients Kl and Kr to a positive constant value and the other yaw control coefficient. When the control coefficient is decreased and the PID output decreases, the other yaw control coefficient of the two yaw control coefficients Kl and Kr is set to a positive constant value, and one yaw control coefficient is decreased.

  In the example of FIG. 7, the slope with respect to the PID output when the yaw control coefficient decreases is constant regardless of whether the yaw control coefficients Kl and Kr are positive or negative, but each yaw control coefficient Kl and Kr decreases. In this case, the slope with respect to the PID output can be made different depending on whether the yaw control coefficients Kl and Kr are positive or negative.

2 and 3, the main correction coefficient acquisition unit 80 outputs the two yaw control coefficients Kl and Kr acquired according to the PID output to the correction means 82 included in the control means 74. Control means 74 includes correction means 82, torque command calculation means 84, and motor control means 64. Correcting means 82, a target rotational speed command value of 2, the target rotational speed command value of the electric motor 22 for the left wheel and the right wheel motor 24 Vrl ^*, each Vrr ^*, the yaw control coefficient corresponding 2 The corrected target rotational speed command values Vrkl ^* and Vrkr ^* are obtained by correcting with Kl and Kr. That is, the target rotational speed command values Vrl ^*, the Vrr ^*, is multiplied by the corresponding yaw control coefficients Kl, Kr, respectively, the corrected target rotational speed command values for the left and right wheels 18, 20 Vrkl ^*, obtain Vrkr ^*. The torque command calculation means 84 calculates the corrected target rotational speed command values Vrkl ^* and Vrkr ^* and the electric motors 22 and 24 detected by the two rotational speed sensors 62 provided on the left and right wheel electric motors 22 and 24. Torque commands τrl and τrr corresponding to the electric motors 22 and 24 are calculated based on the deviation from the rotational speed detection values Vrl and Vrr. For this purpose, the torque command calculation means 84 includes torque command PID calculation units 88 and 90 for the left and right wheels 18 and 20 that perform PID calculation.

  The left wheel torque command PID calculation unit 88 receives the deviation between the corrected target rotation speed command value Vrkl for the left wheel 18 and the rotation speed detection value Vrl of the left wheel electric motor 22, and performs PID calculation. Thus, the torque command τrl of the left wheel electric motor 22 is calculated and input to the motor control means 64 (FIG. 2). The motor control means 64 has a driver circuit including a corresponding inverter, and the corresponding driver circuit controls driving of the left wheel electric motor 22 by a driving voltage corresponding to the torque command.

Similarly, the torque command PID calculation unit 90 for the right wheel 20 receives a deviation between the corrected target rotational speed command value Vrkr ^* for the right wheel 20 and the rotational speed detection value Vrr of the right wheel electric motor 24. The torque command τrr of the right wheel electric motor 24 is calculated by performing PID calculation, and is input to the motor control means 64 (FIG. 2). The corresponding driver circuit included in the motor control means 64 controls the drive of the right wheel electric motor 24 by the drive voltage corresponding to the torque command. In this way, the control means 74 corrects each of the two target rotational speed command values with a correction coefficient of 2, and based on the corrected two target rotational speed command values, the two wheel electric motors 22, The drive of 24 is controlled. The controller 48 controls driving of the left and right wheel electric motors 22 and 24 based on detection signals of various sensors including the accelerator depression amount, the steering angle, and the yaw rate. In addition, when the absolute value of the output of the PID calculation unit 78 is equal to or greater than a predetermined value, the controller 48 calculates a yaw control coefficient corresponding to one wheel electric motor among the two wheel electric motors 22 and 24. As a negative value, the driving of each of the electric motors 22 and 24 is controlled so as to generate a driving torque in the reverse direction with respect to the positive rotation corresponding to the traveling direction in one wheel electric motor.

  Each function of the controller 48 can be configured by a computer except for a driver circuit portion. Each of the above functions can be realized by software, specifically, by executing a lawnmower vehicle control program. Of course, a part of each of the above functions can be realized by hardware.

According to such a lawnmower vehicle 10, operating the two target rotational speed command values of the electric motors 22 and 24 for wheels of each 2 based on the acceleration instruction and a turn instruction input by user Vrl ^*, Vrr ^* is calculated The target yaw rate γ ^* is calculated based on the acceleration instruction and the turning instruction, and the two wheel electric motors 22 and 24 are respectively determined based on the deviation between the target yaw rate γ ^* and the yaw rate detection value γ of the yaw rate sensor 60. Two related correction coefficients Kl and Kr are obtained. Further, the two target rotational speed command values Vrl ^* and Vrr ^* are corrected by the correction coefficients Kl and Kr of 2, respectively. Based on the corrected two target rotational speed command values Vrkl ^* and Vrkr ^* , The driving of the wheel electric motors 22 and 24 is controlled. For this reason, in a configuration in which the left and right wheels 18 and 20 can be independently driven by the two wheel electric motors 22 and 24, even when the vehicle 10 travels on an inclined surface, driving in a straight traveling direction or a turning direction is possible. The vehicle 10 can travel in the direction intended by the person, and can easily set the behavior characteristics of the vehicle 10 during the control action based on the deviation between the detected value of the yaw rate and the target value.

For example, in FIG. 3, when the target yaw rate γ ^* is larger than the detected yaw rate γ when turning to the left side of the vehicle, that is, when the turning radius of the vehicle tends to increase, the PID calculation unit 78 is provided as the PID output. A positive value Q (see FIG. 8) is output, and the main correction coefficient acquisition unit 80 outputs 1 as the right wheel yaw control coefficient Kr using the map shown in FIG. 8, and the left wheel yaw control coefficient Kl. As a result, a value smaller than 1 is output. For this reason, the corrected target rotational speed command value VrKl ^* for the left wheel 18 becomes small, and as a result, the detected yaw rate γ tends to approach the target yaw rate γ ^* . In this case, in the map of FIG. 8, the left wheel yaw control coefficient Kl changes in the direction indicated by the solid-line arrow and tends to approach 1. When the target yaw rate γ _* and the detected yaw rate γ completely match, the left wheel yaw control coefficient Kl becomes 1, so that the corrected target rotational speed command values VrKl ^* and VrKr ^* for the left and right wheels 18 and 20 are the target. rotational speed command value Vrl ^*, becomes Vrr ^* respectively the same.

Meanwhile, PID for PID calculation unit 78, such as performing operations including integral calculation, the main corrected target rotational speed command value by the output of the coefficient acquiring unit 80 Vrl ^*, and be corrected Vrr ^*, a small effect of correction There is also a possibility that the output becomes large. In this case, the left wheel yaw control coefficient Kl changes in the direction indicated by the broken line arrow in FIG. For example, when the left wheel yaw control coefficient Kl becomes a negative value, the corrected left wheel target rotational speed command value VrKl ^* changes from positive to negative, and this causes the left wheel electric motor 22 to drive in the reverse direction. Corresponds to generating torque. Although the case where the vehicle turns to the left side has been described above, the right wheel yaw control coefficient Kr changes when the vehicle turns to the right side. Because of this configuration, even when the vehicle is traveling on a contour line or turning on a slope, for example, the target rotational speed command value can be corrected so as to eliminate the deviation between the yaw rate detection value and the target yaw rate. Turning in an unintended direction can be prevented, and the vehicle can travel in the direction intended by the driver.

Further, since the two target rotational speed command values Vrl ^* and Vrr ^* are corrected by the correction coefficients Kl and Kr of 2, respectively, the setting of the correction coefficients Kl and Kr of 2 can be easily changed, and the yaw rate It is possible to easily set the behavioral characteristics of the vehicle during the control action based on the deviation between the detected value and the target value. For example, the relationship between the PID output and the correction coefficients Kl and Kr can be easily changed by changing the setting of the map that preliminarily defines the two correction coefficients Kl and Kr. For example, the map shown in FIG. 7 is an example, and as the slope of the yaw control coefficients Kl and Kr with respect to the PID output is changed, or as the absolute value of the PID output increases as shown in FIG. Both yaw control coefficients Kl and Kr can be gradually reduced. Further, as shown in FIG. 10, only one of the two yaw control coefficients Kl and Kr can be gradually increased as the absolute value of the PID output increases.

Further, the controller 48 proceeds in one wheel electric motor 22 (or 24) out of the two wheel electric motors 22 and 24 when the absolute value of the output of the PID calculation unit 78 becomes a predetermined value or more. The drive of each of the electric motors 22 and 24 is controlled so as to generate a drive torque in the reverse direction with respect to the normal rotation corresponding to the direction. That is, when the vehicle moves forward, one wheel electric motor 22 (or 24) generates a driving torque in the reverse direction with respect to the forward rotation corresponding to the forward direction. In addition, when the vehicle is moving backward, one wheel electric motor 22 (or 24) is caused to generate a driving torque in the reverse direction with respect to the normal rotation corresponding to the reverse direction. For this reason, even when the deviation between the target yaw rate γ ^* and the yaw rate detection value γ is large, the deviation can be eliminated more quickly and stable running can be easily realized.

  In the present embodiment, the steered wheels are caster wheels 14 and 16, but instead of the caster wheels 14 and 16, a mechanical steering type operatively connected to a steering operator 50 via a steering mechanism. Steering wheels can also be used. The steering mechanism includes, for example, a rack and pinion mechanism that converts the rotational force of the steering shaft connected to the steering operator 50 into a linear force, and the left and right steering operations are performed by pushing and pulling the rack shaft in conjunction with the rotation of the steering shaft. The steering wheel is configured to be steerable.

  In this embodiment, the PID calculation unit 78 is used as the calculation unit included in the correction coefficient acquisition unit 72. However, instead of the PID calculation unit 78, a PI calculation unit that performs PI calculation can also be used. .

[Second Embodiment]
FIG. 11 shows a lawnmower vehicle 10 that is a riding type ground working vehicle according to a second embodiment of the present invention. FIG. 12 is a block diagram illustrating a functional configuration of the controller 48 in the lawnmower vehicle 10 according to the second embodiment. As shown in FIG. 11, in the case of the lawnmower vehicle 10 of the present embodiment, the steering operator 50 and the forward and reverse accelerator pedals 52 and 54 are omitted in the case of the first embodiment. Instead, left and right levers 92 and 94, which are two-lever type operation elements, are provided as acceleration operation elements and turning operation elements. The left and right levers 92 and 94 are provided at positions separated on the left and right sides of the seat 46 (see FIG. 17), and can swing back and forth about a horizontal swing center shaft 96 extending in the left and right directions. A portion fixed to the frame 12 is supported.

  By swinging the left lever 92 forward or backward, the left wheel electric motor 22 can be driven in the forward or reverse direction, and the rotational speed of the left wheel electric motor 22 is increased by increasing the swing amount. And the rotational speed is lowered by reducing the swing amount. Similarly, by swinging the right lever 94 forward or backward, the right wheel electric motor 24 can be driven in the forward or reverse direction, and by increasing the swing amount, the right wheel electric motor 24 is driven. The rotation speed is increased, and the rotation speed is decreased by reducing the swing amount. That is, the left and right levers 92 and 94 can input the rotational speeds of the left and right wheel electric motors 22 and 24 as acceleration instructions and turning instructions. That is, the two-lever type operating elements can input acceleration instructions and turning instructions in cooperation with each other.

The left and right levers 92 and 94 are detected by the left lever sensor 98 and the right lever sensor 100, respectively. The detected values are sent to the controller 48 as shown in FIG. Is transmitted. As shown in FIG. 12, the controller 48 includes a command value calculation unit 68, a target yaw rate calculation unit 70, a correction coefficient acquisition unit 72, and a control unit 74 as in the first embodiment. In the following description, the same elements as those in FIG. The command value calculation means 68 uses the left and right lever sensors 98 and 100 to obtain acceleration instructions and turning instructions input by the driver, that is, operation values, and based on these operation values, two wheel electric motors 22 and 24 each of the two target rotational speed command values Vrl ^*, calculates the Vrr ^*. In this case, the command value calculating unit 68, in response to the detected values of the lever sensor 98, 100, the target rotational speed command value for the target rotational speed command values Vrl ^* and the right wheel 20 for the left wheel 18 Vrr ^* and Are calculated respectively. The target rotational speed command values Vrl ^* and Vrr ^* are positive values when the electric motors 22 and 24 generate drive torque in the forward rotation direction corresponding to the forward side, and correspond to the reverse side of the electric motors 22 and 24. A negative value is used when drive torque is generated in the reverse direction.

Meanwhile, the target yaw rate calculating section 70, the calculated target rotational speed command values Vrl ^*, from Vrr ^*, calculates the target yaw rate gamma ^*. Further, the correction coefficient acquisition means 72 performs two corrections related to the two wheel electric motors 22 and 24 based on the deviation between the target yaw rate γ ^* and the yaw rate detection value γ detected by the yaw rate sensor 60. The coefficients Kl and Kr are acquired. The functions of the target yaw rate calculation means 70 and the correction coefficient acquisition means 72 are the same as those in the case of the first embodiment. The control means 74, the yaw control coefficient Kl for the left and right wheels 18 and 20 output by the correction coefficient acquiring section 72, the target rotational speed command values by Kr Vrl ^*, corrects the Vrr ^*. Other configurations and operations are the same as those in the first embodiment.

[Third Embodiment]
FIG. 13 shows a lawnmower vehicle 10 that is a riding-type ground working vehicle according to a third embodiment of the present invention. FIG. 14 is a diagram illustrating a configuration of the lawnmower vehicle 10 according to the third embodiment. FIG. 15 is a block diagram showing a functional configuration of the controller 48 of FIG. In FIG. 14, lever sensors 98 and 100 which are components of a fourth embodiment to be described later are also shown in parentheses. In the present embodiment, left and right wheel hydraulic motors 102 and 104, which are travel motors, are provided in place of the left and right wheel electric motors 22 and 24 in the first embodiment shown in FIGS. ing. Further, the lawnmower vehicle 10 is provided with an engine 38 (FIG. 14) as an actuator power source and a hydraulic pump unit 106 as an actuator driven by the engine 38. The hydraulic pump unit 106 includes two hydraulic pump bodies 108 and 110 and two control shaft electric motors 112 and 114 corresponding to the respective hydraulic pump bodies 108 and 110. The two hydraulic pump bodies 108 and 110 are illustrated. The pump shafts that are not connected are operatively connected by a power transmission mechanism such as a gear mechanism. The engine 38 may be a horizontal type whose output shaft is oriented in the horizontal direction, or may be a vertical type whose output shaft is oriented in the vertical direction.

  Of the pump shafts of the two hydraulic pump bodies 108 and 110, one pump shaft is driven by the engine 38. For this reason, one pump shaft is driven by driving the engine 38, and the other pump shaft is also driven through the power transmission mechanism. The hydraulic pump bodies 108 and 110 are movable swash plate type variable displacement pumps, and the rotation angles of the two control shafts 118 and 120 corresponding to the respective tilts of the movable swash plate (not shown) rotatably supported by the pump case 116. It can be adjusted by changing The rotation angles of the two control shafts 118 and 120 that are arranged parallel to each other and rotatable are changed by the corresponding control shaft electric motors 112 and 114. For example, in the example of FIG. 13, the control shafts 118 and 120 are arranged so as to face the vertical direction of the lawnmower vehicle 10 (the front and back direction of FIG. 13). Each control shaft electric motor 112, 114 is operatively connected to a corresponding control shaft 118, 120 and changes the rotation angle of the corresponding control shaft 118, 120. Further, by changing the inclination of the movable swash plate, the amount and flow direction of the pressure oil sucked or discharged from the corresponding hydraulic pump bodies 108 and 110 can be changed. The hydraulic pump bodies 108 and 110 are, for example, axial piston types. However, each of the hydraulic pump bodies 108 and 110 can adopt other types such as a radial piston type.

  The discharge ports 122 and 124 of the two hydraulic pump bodies 108 and 110 are connected to the left and right wheel hydraulic motors 102 and 104 via pipe lines so as to allow discharge and suction of pressure oil to and from the discharge ports 122 and 124, respectively. ing. When hydraulic oil discharged from the hydraulic pump bodies 108 and 110 is supplied to the hydraulic motors 102 and 104, the hydraulic motors 102 and 104 are driven. As the amount of pressure oil discharged from the hydraulic pump bodies 108 and 110 increases, the rotational speed of the hydraulic motors 102 and 104 increases, and when the amount of pressure oil discharged from the hydraulic pump bodies 108 and 110 decreases, the hydraulic motors 102 and 104 increase. The rotational speed of 104 becomes low.

  Each of the hydraulic pump bodies 108 and 110 has two discharge ports 122 and 124. One of the two discharge ports 122 and 124 functions as pressure oil discharge, and the other functions as pressure oil suction. In response to switching of the direction in which the hydraulic motors 102 and 104 are rotated, the discharge ports 122 and 124 that function as pressure oil discharge and the discharge ports 122 and 124 that function as pressure oil suction are switched. Thus, each of the hydraulic pump bodies 108 and 110 can discharge pressure oil independently from the two discharge ports 122 and 124, and the hydraulic pump unit 106 has a rotation angle of the two control shafts 118 and 120. By changing, the discharge amount of the pressure oil discharged from the two discharge ports 122 and 124 corresponding to the two control shafts 118 and 120 is changed. Further, when the flow direction of the pressure oil from the hydraulic pump main bodies 108 and 110 corresponding to the respective hydraulic motors 102 and 104 is switched, the forward rotation and the reverse rotation of the respective hydraulic motors 102 and 104 are switched.

  Each of the control shaft electric motors 112 and 114 rotates in the forward rotation direction or the reverse rotation direction when electric power is supplied from the battery 42 (see FIG. 2) via a driver circuit constituting the controller 48. The output shafts of the control shaft electric motors 112 and 114 are operatively connected to the control shafts 118 and 120 via a clutch mechanism and a worm transmission mechanism (not shown) and a sector transmission mechanism 126. The worm transmission mechanism includes a worm shaft provided on the output shafts of the control shaft electric motors 112 and 114 so that power can be transmitted via a clutch mechanism, and a worm wheel meshing with the worm shaft. The sector transmission mechanism 126 includes an output gear coupled to the worm wheel so as not to rotate relative to the worm wheel, and a sector gear including a substantially fan-shaped portion meshed with the output gear. The control shafts 118 and 120 are coupled to the sector gear so as not to rotate relative to each other. An engagement arm (not shown) is provided at the opposite end of the sector gear control shaft 118, 120, and a rotation range of the sector gear is achieved by making a stopper portion fixed to the pump case on both sides of the engagement arm through a space. Is regulated within a predetermined range.

  The clutch mechanism includes a reverse rotation prevention mechanism that prevents the worm shaft from rotating by a force from the pump shaft side while allowing the worm shaft to rotate according to the rotation of the control shaft electric motors 112 and 114. Such a clutch mechanism enables the movable swash plate to be tilted by the control shaft electric motors 112 and 114 while preventing the movable swash plate from tilting unexpectedly from the set tilt position. The

  The hydraulic pump unit 106 is provided with two rotation angle sensors 128 (FIG. 14) for detecting the rotation positions of the control shafts 118 and 120, that is, the rotation angle positions. Each rotation angle sensor 128 is configured by making a detection unit fixed to the pump case 116 face a detection unit provided in a portion that rotates together with the control shafts 118 and 120. For example, in FIG. 13, illustration of the rotation angle sensor 128 is omitted, but the two rotation angle sensors 128 are arranged coaxially with the control shafts 118 and 120 and so as to cover the upper sides of the control shafts 118 and 120. You can also The detection signal of each rotation angle sensor 128 is input to the motor control means 130 constituting the controller 48.

  Each hydraulic motor 102, 104 is provided with a rotational speed sensor 132 which is a rotational speed detecting means for detecting the rotational speed of each hydraulic motor 102, 104. The detection signal of each rotation speed sensor 132 is input to the controller 48. Each hydraulic motor 102, 104 is provided with a rotation angle sensor instead of the rotation speed sensor 132, and a detection signal of the rotation angle sensor is input to rotation speed calculation means constituting the controller 48, and each hydraulic motor is determined from the rotation angle detection value. The rotational speeds 102 and 104 can also be calculated. In this case, the rotation angle sensor and the rotation speed calculation means constitute a rotation speed detection means.

  Further, the controller 48 uses the detection signals of these various sensors and the detection signals of the accelerator depression sensor 58 and the steering angle sensor 56 to independently control the rotational speeds of the left and right wheel hydraulic motors 102 and 104. Control. For this purpose, the rotation angle command values of the two control shaft electric motors 112 and 114 corresponding to the left and right wheel hydraulic motors 102 and 104 that drive the left and right wheels 18 and 20 are calculated, respectively, and correspond to the respective rotation angle command values. Then, the drive of each control shaft electric motor 112, 114 is feedback controlled so that the actual rotation angle can be obtained. Next, with reference to FIGS. 14 and 15, the configuration and functions of the controller 48 will be described with a focus on differences from the case of the first embodiment shown in FIGS. 1 to 10.

As shown in FIG. 14, the controller 48 includes a command value calculation unit 68, a target yaw rate calculation unit 70, a correction coefficient acquisition unit 72, and a control unit 134. The functions of the command value calculation means 68, the target yaw rate calculation means 70, and the correction coefficient acquisition means 72 are the same as those in the first embodiment. The control unit 134 includes a correction unit 82, a rotation angle command calculation unit 136, and a motor control unit 130. Correcting means 82, a target rotational speed command value of 2, the target rotational speed command values of the left and right wheel hydraulic motors 102, 104 Vrl ^*, each Vrr ^*, corresponding two of the yaw control coefficient Kl, corrected by Kr Thus, the corrected target rotational speed command values VrKl ^* and VrKr ^* are obtained. The rotation angle command calculation means 136 includes the corrected target rotation speed command values VrKl ^* and VrKr ^* and the respective hydraulic motors 102 detected by the two rotation speed sensors 132 provided on the left and right wheel hydraulic motors 102 and 104. Based on the deviation from the detected rotational speed values Vrl and Vrr of 104, pre-correction rotational angle command values Posl ^* and Posr ^* for the control shaft electric motors 112 and 114 are calculated. The pre-correction rotation angle command values Posl ^* and Posr ^* correspond to the discharge amounts and discharge directions of the hydraulic pump bodies 108 and 110 corresponding to the hydraulic motors 102 and 104, respectively. Further, the rotation angle command calculation means 136 calculates the rotation angle commands Posl and Posr by correcting using the rotation angle detection values of the control shaft electric motors 112 and 114. For this purpose, the rotation angle command calculation means 136 performs the PID calculation based on the deviation, the first PID calculation units 138 and 140 for the left and right wheels 18 and 20, the subtraction units 142 and 144, and the second PID calculation unit 146. , 148.

As shown in FIG. 15, the first PID calculation unit 138 for the left wheel 18 receives a deviation between the corrected target rotation speed command value VrKl ^* and the rotation speed detection value Vrl of the left wheel hydraulic motor 102, and performs PID calculation. To calculate the pre-correction rotation angle command value Posl ^* of the control shaft electric motor 112 for the left wheel 18. The subtraction unit 142 outputs the deviation between the pre-correction rotation angle command value Posl ^* and the rotation angle detection value Posl of the control shaft electric motor 112 to the second PID calculation unit 146 for the left wheel 18 to perform PID calculation. Thus, the rotation angle command value Posl of the control shaft electric motor 112 for the left wheel 18 is calculated and input to the motor control means 130. The motor control means 130 has a driver circuit including a corresponding inverter, and the corresponding driver circuit controls driving of the control shaft electric motor 112 for the left wheel 18 in accordance with the rotation angle command. As a result, the drive of the left wheel hydraulic motor 102 is controlled.

Similarly, the first PID calculation unit 140 for the right wheel 20 receives a deviation between the corrected target rotation speed command value VrKr ^* and the rotation speed detection value Vrr of the right wheel hydraulic motor 104, and performs PID calculation. A pre-correction rotation angle command value Posr ^* for the control shaft electric motor 114 for the right wheel 20 is calculated. The subtraction unit 144 outputs the deviation between the pre-correction rotation angle command value Posr ^* and the rotation angle detection value Posr of the control shaft electric motor 114 to the second PID calculation unit 148 for the right wheel 20, and performs PID calculation. Thus, the rotation angle command value Posr of the control shaft electric motor 114 for the right wheel 20 is calculated and input to the motor control means 130. The corresponding driver circuit of the motor control means 130 controls the drive of the control shaft electric motor 114 for the right wheel 20 in accordance with the rotation angle command. As a result, the drive of the right wheel hydraulic motor 104 is controlled.

As described above, the control unit 134 calculates the target rotational speed command values VrKl ^* and VrKr ^* after correction by the correction coefficient and the rotational speed detection values Vrl and Vrr of the two wheel hydraulic motors 102 and 104. Based on the deviation, the rotation angle command values Posl ^* and Posr ^* of the two control shafts 118 and 120 are calculated, and the two control shaft electric motors 112 and 114 are driven by the rotation angle command values Posl ^* and Posr ^*. Control. For this reason, the discharge amount discharged from the two discharge ports 122 and 124 (FIG. 13) corresponding to the respective hydraulic motors 102 and 104 of the hydraulic pump unit 106 changes. Thus, the driving of the two left and right wheel hydraulic motors 102 and 104 is controlled. Since other configurations and operations are the same as those of the first embodiment shown in FIGS. 1 to 10 described above, the same parts are denoted by the same reference numerals and redundant description is omitted.

  In this embodiment, pressure oil is supplied from the two hydraulic pump bodies 108 and 110 included in one hydraulic pump unit 106 to the hydraulic motors 102 and 104 for the left and right wheels 18 and 20. However, as the hydraulic pump unit 106, a structure of two hydraulic pump units, which are two actuators, separated from each other for the left and right wheels 18 and 20 with respect to the hydraulic pump and the electric motor for the control shaft is adopted. You can also In this case, the power of the engine can be transmitted to each of the two hydraulic pump units by the power transmission mechanism. Also, each of the two hydraulic pump units can be integrated with a housing that houses the two hydraulic motors 102 and 104 for the left and right wheels 18 and 20 and the speed reduction mechanism. In this case, two discharge ports of each of the two hydraulic pump units and the hydraulic motors 102 and 104 are connected to each other via a conduit so as to be able to discharge and suck pressure oil to and from the discharge ports.

[Fourth Embodiment]
FIG. 16 shows a lawnmower vehicle 10 that is a riding type ground working vehicle according to a fourth embodiment of the present invention. FIG. 17 is a schematic view of the vehicle 10 of FIG. 16 viewed in the horizontal direction. FIG. 18 is a block diagram illustrating a functional configuration of the controller 48 in the lawnmower vehicle 10 according to the fourth embodiment. In the present embodiment, the configuration of the third embodiment shown in FIGS. 13 to 15 is combined with the second embodiment shown in FIGS. That is, in the case of the third embodiment, the lawnmower vehicle 10 serves as an acceleration operator and a turning operator instead of omitting the steering operator 50 and the forward and reverse accelerator pedals 52 and 54. The left and right levers 92 and 94, which are two lever type operating elements similar to those in the second embodiment, are provided. The left and right levers 92 and 94 are provided at positions separated on the left and right sides of the seat 46. That is, the two-lever type operating elements can input acceleration instructions and turning instructions in cooperation with each other.

The left and right lever sensors 98 and 100 detect the swing amount and the swing direction of the left and right levers 92 and 94, and the detection signal is transmitted to the controller 48. Similarly to the third embodiment shown in FIG. 14, the controller 48 includes a command value calculation unit 68, a target yaw rate calculation unit 70, a correction coefficient acquisition unit 72, and a control unit 134. The command value calculation means 68 uses the left and right lever sensors 98 and 100 to determine the acceleration and turning instructions input by the driver, that is, two of the two wheel hydraulic motors 102 and 104, respectively, based on the operation value. target rotational speed command values Vrl ^*, calculates the Vrr ^*. Other configurations and operations are the same as those of the third embodiment shown in FIGS. 13 to 15 or the second embodiment shown in FIGS. In the case of the configuration shown in FIG. 16 as well, as in the third embodiment shown in FIG. 13, for example, the control shafts 118 and 120 are directed in the vertical direction of the lawn mower vehicle 10 (the front and back direction in FIG. 13). The two rotation angle sensors 128 that detect the rotation angle positions of the control shafts 118 and 120 are coaxial with the control shafts 118 and 120 and cover the upper sides of the control shafts 118 and 120, respectively. It can also be arranged.

[Fifth Embodiment]
FIG. 19 is a perspective view showing a lawnmower vehicle 10 which is a riding type ground working vehicle according to a fifth embodiment of the present invention. FIG. 20 is a perspective view showing the rotation support structure of the steering operator provided in the lawnmower vehicle 10 according to the fifth embodiment. FIG. 21 is an enlarged view showing a state where the AA portion of FIG. 20 is cut and the upper spring and the lower spring are removed. FIG. 22 is a diagram showing a state in which the steering operator is rotated from the neutral position to one side in a time series, and is a view of a part of FIG. FIG. 23 shows the relationship between the steering operation force and the steering angle, which shows that the degree of increase in the steering operation force changes with a predetermined steering angle threshold when rotating the steering operator in the fifth embodiment. FIG.

  As shown in FIG. 19, in the present embodiment, the lawnmower vehicle 10 has a forward accelerator on the upper side of the main frame 12 that is a vehicle body, as in the first embodiment shown in FIGS. A pedal 52, a reverse accelerator pedal 54, and a brake pedal 149 are provided. As shown in FIG. 19, the swing support portions of the links of the forward and reverse accelerator pedals 52 and 54 are arranged on the front side of the front panel 150 when the vehicle is viewed from the rear. It may be arranged on the back side of the front panel 150.

  A storage chamber 152 for storing a controller and a battery (not shown) is provided in a substantially U-shaped range on the upper side of the main frame 12 and including the left and right sides of the driver's seat 46 and the rear side (the right side in FIG. 19). Covered with a cover 154. Note that the cover 154 can be made detachable by dividing the substantially U-shaped portion into a plurality of parts.

  A support portion 156 made of a metal plate such as a steel plate is erected on the front portion of the main frame 12 (left portion in FIG. 19), and the steering box 158 is fixed to the upper side of the center portion in the left-right direction of the support portion 156. ing. A steering operator 50 is rotatably supported on the steering box 158, and a steering angle thereof can be detected by a steering angle sensor 56 (FIG. 20). Next, the rotation support structure of the steering operator 50 will be described in detail with reference to FIG.

  20 is a view showing the steering box 158 with the steering box 158 removed. The steering operator 50 includes a circular rim portion, a radial spoke portion coupled to the rim portion, and a steering shaft portion 160 coupled to the center portion of the spoke. including. A support frame 162 is fixed on the upper side of the support portion 156 (FIG. 19), and is called a bearing stay so as to be separated vertically on one side of the upper end portion of the support frame 162 (left side in FIG. 20). An upper bearing support portion 164 and a lower bearing support portion 166 that are fixed portions are provided.

  The support frame 162 may be fixed to the main frame 12 (FIG. 19) without the support portion 156 (FIG. 19). Each of the upper and lower bearing support portions 164 and 166 is provided with a bearing inside, and two portions of the steering shaft portion 160 are rotatably supported by the respective bearings. For example, as shown in FIG. 21, a bearing 168 such as a ball bearing is provided around the steering shaft portion 160, and the steering shaft portion 160 is rotatably supported by the bearing 168 on the upper bearing support portion 164 (FIG. 20). ing.

  A steering angle sensor 56 is provided at the lower end of the steering shaft 160. In the case of this example, the steering angle sensor 56 has a casing fixed to the lower side of the lower bearing support portion 166 as a potentiometer. Further, a detector of the steering angle sensor 56 is connected to the lower end of the steering shaft portion 160, and the steering angle of the steering operator 50 (FIG. 20) can be detected by the steering angle sensor 56. The detection signal of the steering angle sensor 56 is taken out by the cable 170 and input to a controller (not shown). As the steering angle sensor 56, an electrical sensor such as an encoder, an optical sensor, or the like other than the potentiometer can be used. Note that the steering angle sensor 56 can be provided on another member that works in conjunction with the steering shaft portion 160 or on the periphery thereof, in addition to the lower end portion of the steering shaft portion 160.

  As shown in FIG. 20, a swing arm 172 is fixed between the upper and lower bearing support portions 164 and 166 of the steering shaft portion 160. As shown in FIG. 21, the swing arm 172 includes a main body portion 174 formed in a substantially rhombic flat plate shape, and a first upper locking pin 176 fixed to both end portions of the main body portion 174 so as to protrude downward. And an abutting pin 178. The swing arm 172 is integrated with the steering shaft portion 160 and swings in the same direction as the rotation direction of the steering shaft portion 160 as the steering shaft portion 160 rotates.

  Further, a loose fitting arm 180 is loosely fitted between the swing arm 172 of the steering shaft portion 160 and the lower bearing support portion 166. That is, the loosely fitting arm 180 is externally supported so as to be rotatable relative to the steering shaft portion 160. A bearing such as a ball bearing may be provided between the steering shaft portion 160 and the loose fitting arm 180. The loose fitting arm 180 is formed larger than the swing arm 172. The loose-fitting arm 180 is plate-like as a whole, and has a main body part 182 having a shape in which a semicircular part 192 is coupled to a chevron part 190, a first lower locking pin 184 fixed to the main body part 182, and a second upper side. A locking pin 186 and a stopper 188 provided on the upper side of the main body 182 are included. That is, the first lower locking pin 184 is fixed to the top of the chevron 190 of the loosely fitting arm 180 so as to protrude downward. The lower ends of the first upper locking pin 176 and the butting pin 178 of the swing arm 172 are opposed to the upper surface of the loosely fitting arm 180. Further, a second upper locking pin 186 that protrudes upward is fixed to an intermediate portion of the chevron 190.

  Further, as shown in FIG. 22, a pair of stoppers 188 are provided on both sides of the semicircular portion 192 of the loosely fitting arm 180. Each stopper 188 is configured by connecting a bolt to a screw hole of the support portion 194 fixed to the semicircular portion 192 and projecting the front end portion of the bolt from the end surface of the support portion 194. Further, the rotation prevention nut 196 is coupled to the bolt, and the rotation prevention nut 196 is pressed against the support portion 194, thereby preventing an unintended change in the protruding amount of the bolt. Thereby, the protrusion amount from the support part 194 end surface of the front-end | tip part of a volt | bolt can be adjusted, and the state after adjustment can be maintained. The front end surface of each bolt can be abutted against a butting pin 178 fixed to the swing arm 172.

  For example, when the absolute value of the rotation angle from the neutral position (the position shown in FIG. 22A) of the steering shaft 160 is equal to or greater than a predetermined value (for example, 80 degrees), the abutting pin 178 abuts against the stopper 188. It is configured. The abutting mechanism 198 is configured by the abutting pin 178 and the stopper 188. Such an abutment mechanism 198 is provided between the swing arm 172 and the loose-fitting arm 180, and the swing amount from the position of FIG. 22 (a) which is the neutral position of the swing arm 172 is set in advance. Only when the amount is equal to or larger than the predetermined amount, the swing arm 172 is abutted against the loosely fitting arm 180, and the loosely fit arm 180 is integrally swung in the same direction as the swing arm 172.

  Further, as shown in FIG. 21, the fixing member 200 is fixed on the upper side of the lower bearing support portion 166 that supports the lower end portion of the steering shaft portion 160, and the upper surface of the fixing plate 202 provided on the fixing member 200 is free of play. The front end surface of the first lower locking pin 184 of the fitting arm 180 is opposed. The second lower locking pin 204 is fixed to the fixing plate 202 so as to protrude upward. A steering shaft portion 160 is fitted in a hole provided in the fixing member 200. The first upper and lower locking pins 176 and 184, the second upper and lower locking pins 186 and 204, and the abutment pin 178 all extend in a direction parallel to the steering shaft portion 160. Yes.

  An upper spring 206, which is a first spring, is loosely fitted between the swing arm 172 and the loosely fitting arm 180 of the steering shaft portion 160. The upper spring 206 is obtained by extending a pair of legs 208, which are both ends of the coil spring, in a substantially parallel direction. The upper spring 206 loosely fits the main body of the upper spring 206 to the steering shaft 160, and a pair of legs. The first upper locking pin 176 of the swing arm 172 and the second upper locking pin 186 of the loose-fitting arm 180 are arranged inside the portion 208 so as to sandwich it. Thereby, for example, as shown in FIGS. 22A to 22C, when the steering shaft portion 160 rotates in either direction, the swing arm 172 swings with respect to the loose fitting arm 180. The interval between the first upper locking pin 176 and the second upper locking pin 186 increases, and the interval between the pair of leg portions 208 pressed by these locking pins 176 and 186 increases. In this case, an urging force that is an elastic force in a direction of reducing the distance between the pair of leg portions 208 from the pair of leg portions 208 is applied to the upper locking pins 176 and 186. For this reason, in order to rotate the steering shaft portion 160, it is necessary to apply an operating force that resists the biasing force of the upper spring 206. That is, the upper spring 206 biases the swing arm 172 with a biasing force that increases as the swing amount of the swing arm 172 with respect to the loosely fitting arm 180 increases. Note that FIG. 22 shows a case where the steering operator 50 (FIG. 20) is gradually rotated to the right, but the steering shaft in a direction opposite to the state of FIGS. 22 (a) to (c). The same applies to the case where the portion 160 is rotated, that is, the case where the steering operator 50 is rotated to the left, except that the left and right sides of the leg portions 208 pressed by the upper locking pins 176 and 186 are reversed.

  Further, as shown in FIG. 21, a lower spring 210, which is a second spring, is loosely fitted between the loosely fitting arm 180 of the steering shaft portion 160 and the lower bearing support portion 166. Similarly to the upper spring 206, the lower spring 210 is also formed by extending a pair of leg portions 212 that are both ends of the coil spring in a substantially parallel direction, and loosely fitting the main body portion of the lower spring 210 to the steering shaft portion 160. I am letting. At the same time, the first lower locking pin 184 of the loosely fitting arm 180 and the second lower locking pin 204 provided on the fixing plate 202 are disposed inside the pair of leg portions 212. The length of the leg portion 212 of the lower spring 210 is made longer than the length of the leg portion 208 of the upper spring 206, and the urging force of the lower spring 210 is made larger than the urging force of the upper spring 206.

  Thus, for example, as shown in FIGS. 22A to 22B, when the absolute value of the rotation angle from the neutral position of the steering shaft 160 is less than a predetermined angle (for example, 80 degrees), the steering shaft 160 is moved. As a resistance force against swinging with respect to the fixed plate 202 (FIG. 21 and the like), an urging force of the upper spring 206, that is, a resistance force based on the elasticity and a resistance force based on the elasticity of the lower spring 210 act. The elasticity of the lower spring 210 is greater than the elasticity of the upper spring 206, and as a result, the positional relationship between the second lower locking pin 204 provided on the fixed plate 202 and the loosely fitting arm 180 does not change. For this reason, the elasticity of the upper spring 206 that increases in response to the swing displacement of the swing arm 172 relative to the loosely-fitting arm 180 acts on the steering shaft portion 160 as a resistance force that increases against the operating force of the steering shaft portion 160. . However, as shown in FIG. 22C, when the absolute value of the rotation angle of the steering shaft portion 160 reaches a predetermined angle (for example, 80 degrees), the abutting pin 178 of the swing arm 172 hits the stopper 188, As shown in (d) of FIG. 22, when the steering shaft portion 160 is further rotated, the swing arm 172 and the loosely fitting arm 180 are rotated together. In this case, the loose-fitting arm 180 swings with respect to the second lower locking pin 204 fixed to the fixed plate 202, and the interval between the first lower locking pin 184 and the second lower locking pin 204 is increased. It spreads and the space | interval of a pair of leg parts 212 pushed by these latching pins 184,204 spreads. Therefore, when the swing arm 172 is swung with respect to the second lower locking pin 204 fixed to the fixed plate 202, it acts as a resistance force that directly increases the elasticity of the lower spring 210 without the upper spring 206 interposed therebetween. . The second urging force, which is the elasticity of the lower spring 210, is a force that acts on the pair of leg portions 212 in a direction that reduces the distance between the pair of leg portions 212. For this reason, in order to rotate the steering shaft portion 160, it is necessary to apply an operating force against the second urging force that is the elasticity of the lower spring 210. In other words, the steering shaft portion 160 has a lower spring 210 that is larger in elasticity than the elasticity of the upper spring 206, that is, the elasticity of the lower spring 210 that increases according to the swinging displacement of the loosely fitting arm 180 with respect to the second lower locking pin 204. Is acting as an increasing resistance force against the operating force of the steering shaft portion 160. That is, the lower spring 210 applies a second urging force, which increases as the swing amount from the neutral position of the loose fitting arm 180 increases, that is, as the swing amount with respect to the second lower locking pin 204 increases, to the loose fit arm 180. Energize.

  According to the present embodiment as described above, the steering operation force required to operate, that is, rotate, the steering operator 50 is increased as the absolute value of the steering angle from the neutral position increases, and a certain steering is performed. The degree of increase in the operating force with respect to the increase in the absolute value of the steering angle can be increased with the angle threshold as a boundary. Further, it is not necessary to use complicated control to obtain this effect, and the setting of the steering angle threshold can be easily adjusted.

  FIG. 23 is a diagram illustrating an example of the relationship between the steering angle in the left-right direction of the steering operator and the steering operation force. In the following description, the same elements as those illustrated in FIGS. 19 to 21 are denoted by the same reference numerals. Moreover, the traveling state of the vehicle and the deceleration state of the wheel electric motor are shown on the lower side of FIG. Note that (a) to (d) shown in the lower part of FIG. 23 correspond to (a) to (d) of FIG. 22 described above. The horizontal axis in FIG. 23 indicates the steering angle. However, the steering angle when the steering angle sensor 56 is rotated from the + side output to the right side is obtained, and the steering angle sensor 56 is rotated from the − side output to the left side. The steering angle in the case of making it can be calculated | required. Therefore, the horizontal axis of FIG. 23 can also be expressed as a + side output and a − side output of the steering angle sensor 56.

  In the example of FIG. 23, for example, when the steering operator 50 is rotated to the right from a straight traveling state of the vehicle, the deceleration amount of the right wheel electric motor 24 (see FIG. 1 and the like) gradually increases. In this case, only the urging force of the upper spring 206 among the upper spring 206 and the lower spring 210 is applied to the steering operator 50. When the right wheel electric motor 24 stops rotating, a belief turn is performed in which the vehicle turns around the ground contact position of the right wheel 20 (see FIG. 1 and the like). In this state, as shown in FIG. 22C, the abutting pin 178 strikes the stopper 188 on one side. When the steering operator 50 is further rotated to the right from this state, as shown in FIG. 23, the second urging force of the lower spring 210 is added to the urging force of the upper spring 206, and the rotation angle of the steering operator 50 is increased. The degree of increase in the steering operation force with respect to is increased, and the operation force of the steering operator 50 is suddenly increased (heavy). Then, a rotational torque in the opposite direction to that of the left wheel electric motor 22 (see FIG. 1 and the like) is generated in the right wheel electric motor 24, and the rotation speeds of both the electric motors 24 and 22 are the same and the rotation direction is reversed. In the state, a super-beat turn called clockwise zero turn is performed.

  Further, when the steering operator 50 is rotated counterclockwise from the straight traveling state of the vehicle, the deceleration amount of the left wheel electric motor 22 (see FIG. 1 and the like) gradually increases. In this case, the left and right are only reversed. This is the same as described above. Other configurations and operations are the same as those of the first embodiment shown in FIGS. In the present embodiment, the degree of increase in the operating force with respect to the increase in the absolute value of the steering angle of the steering operator 50 is switched to two stages, but by increasing the number of springs and arms, there are a plurality of stages of three or more stages. It can also be made switchable.

  10 lawn mower vehicle, 12 main frame, 14 left caster wheel, 16 right caster wheel, 18 left wheel, 20 right wheel, 22 left wheel electric motor, 24 right wheel electric motor, 26, 28 power generation unit, 30 housing, 32 Lawn mower (more), 34 More deck, 36 Lawn mowing blade, 38 Engine, 40 Generator, 42 Battery, 44 Power transmission mechanism, 46 Seat, 48 Controller, 50 Steering operator, 52 Forward accelerator pedal, 54 Reverse accelerator pedal, 56 steering angle sensor, 58 accelerator depression sensor, 60 yaw rate sensor, 62 rotational speed sensor, 64 motor control means, 66 storage unit, 68 command value calculation means, 70 target yaw rate calculation means, 72 correction coefficient acquisition means 74 Control means, 76 steer Characteristic acquisition unit, 78 PID calculation unit, 80 main correction coefficient acquisition unit, 82 correction unit, 84 torque command calculation unit, 88, 90 PID calculation unit for torque command, 92 left lever, 94 right lever, 96 swing central axis , 98 Left lever sensor, 100 Right lever sensor, 102 Left wheel hydraulic motor, 104 Right wheel hydraulic motor, 106 Hydraulic pump unit, 108, 110 Hydraulic pump body, 112, 114 Control shaft electric motor, 116 Pump case, 118 , 120 control shaft, 122, 124 discharge port, 126 sector transmission mechanism, 128 rotation angle sensor, 130 motor control means, 132 rotation speed sensor, 134 control means, 136 rotation angle command calculation means, 138, 140 1st PID calculation unit, 142,144 subtraction unit, 146,148 second PI Arithmetic unit, 150 panel, 152 storage chamber, 154 cover, 156 support unit, 158 steering box, 160 steering shaft unit, 162 support frame, 164 upper bearing support unit, 166 lower bearing support unit, 168 bearing, 170 cable, 172 Swing arm, 174 body portion, 176 first upper locking pin, 178 abutting pin, 180 loose fitting arm, 182 body portion, 184 first lower locking pin, 186 second upper locking pin, 188 stopper, 190 Yamagata, 192 Semicircle, 194 Support, 196 Non-rotating nut, 198 Abutment mechanism, 200 Fixing member, 202 Fixing plate, 204 Second lower locking pin, 206 Upper spring, 208 Leg, 210 Bottom Spring, 212 legs.

Claims (8)

Left and right wheels, which are main drive wheels driven independently by the left wheel travel motor and the right wheel travel motor ,
Steering wheels provided away from the left and right wheels in the front-rear direction;
A working machine driven to perform ground work;
A riding type ground work vehicle comprising:
The target rotational speed command value for the left wheel and the right wheel of the driving motor for the left wheel and the right wheel is calculated from the detection signal of the acceleration instruction of the acceleration operator and the turning instruction of the turning operator input by the driver. Command value calculating means for
Yaw rate detection means for detecting the yaw rate of the vehicle;
Target yaw rate calculating means for calculating a target yaw rate based on the acceleration instruction and the turning instruction;
Correction coefficient acquisition means for acquiring a correction coefficient for the left wheel and the right wheel related to the driving motor for the left wheel and the right wheel , respectively, based on the deviation between the target yaw rate and the detected yaw rate value;
Each of the target rotational speed command value for the left wheel and the right wheel is corrected by the correction coefficient for the left wheel and the right wheel, and based on the corrected target rotational speed command value for the left wheel and the right wheel , Control means for controlling the driving of the driving motor for the left wheel and the right wheel ;
A fixed portion that rotatably supports a shaft portion provided on the turning operator and is fixed to the vehicle body;
A swing arm fixed to the shaft portion and swinging as the shaft portion rotates;
A loose-fitting arm loosely fitted between the swing arm of the shaft part and the fixed part;
The swing arm is provided between the swing arm and the loose fitting arm, and the swing arm is abutted against the loose fit arm only when the swing amount from the neutral position of the swing arm is equal to or larger than a predetermined amount. An abutment mechanism that integrally swings the arm in the same direction as the swing arm;
A first spring that is provided between the swing arm and the loosely fitting arm and biases the swinging arm with a biasing force that increases as the swing amount of the swingable arm with respect to the loosely fitted arm increases;
A second spring provided between the loosely-fitting arm and the fixing part and configured to urge the loosely-fitting arm with a second urging force that increases as the swinging amount of the loosely-fitting arm with respect to the fixing part increases. A featured riding-type ground work vehicle. In the riding type ground work vehicle according to claim 1,
Travel motor for the left wheel and the right wheel are respectively the electric motor,
Furthermore, it comprises rotation speed detection means for the left wheel and the right wheel for detecting the rotation speed of the traveling motor for the left wheel and the right wheel ,
The control means performs the respective travel based on the deviation between the target rotational speed command value for the left wheel and the right wheel after correction by the correction coefficient and the rotational speed detection value of the traveling motor for the left wheel and the right wheel. A riding type ground work vehicle characterized by calculating a torque command value of a motor and controlling driving of a driving motor for a left wheel and a right wheel by each torque command value. In the riding type ground work vehicle according to claim 1,
Travel motor for the left wheel and the right wheel, a hydraulic motor, respectively,
Furthermore, the pressure oil can be discharged and independently from at least two discharge ports to travel motor for the left wheel and the right wheel, one capable of changing the discharge amount of pressure oil discharged from the two discharge ports Or two actuators,
Rotation speed detecting means for the left wheel and the right wheel for detecting the rotation speed of the driving motor for the left wheel and the right wheel ,
Based on the deviation between the target rotational speed command value for the left wheel and the right wheel after correction by the correction coefficient , and the rotational speed detection value of the driving motor for the left wheel and the right wheel , A riding-type ground working vehicle characterized by controlling driving of a left and right wheel driving motor by changing a discharge amount of pressure oil discharged from a discharge port. The riding type ground work vehicle according to claim 3,
An actuator power source for driving the actuator,
One or two actuators, the two control axes, is operatively connected to the two control axes, and a two control axis motor for changing the rotation angle of the two control axes, the two control axes An actuator in which the discharge amount of the pressure oil discharged from the two discharge ports corresponding to each of the two control axes is changed by changing the rotation angle.
Based on the deviation between the target rotational speed command value for the left wheel and right wheel after correction by the correction coefficient and the rotational speed detection value of the driving motor for the left wheel and right wheel , By controlling the rotation angle command value of the control shaft and controlling the drive of the two control shaft motors according to the respective rotation angle command values, the drive of the driving motor for the left wheel and the right wheel is controlled. Passenger type ground working vehicle. The riding type ground working vehicle according to any one of claims 1 to 4,
Correction coefficient acquisition means
A calculation unit that performs a calculation including a PI calculation based on a deviation between the target yaw rate and the yaw rate detection value;
A main correction coefficient acquisition unit that acquires correction coefficients for the left wheel and the right wheel corresponding to the target rotational speed command values for the left wheel and the right wheel from the output of the calculation unit,
The main correction coefficient acquisition unit, when the output of the calculation unit increases, out of the correction coefficient for the left wheel and the right wheel , one correction coefficient is a constant value, and the other correction coefficient is decreased or increased, When the output of the calculation unit decreases, among the correction factors for the left wheel and the right wheel , the other correction factor is set to a constant value, and one of the correction factors is decreased or increased. Work vehicle. The riding type ground working vehicle according to any one of claims 1 to 4,
Correction coefficient acquisition means
A calculation unit that performs a calculation including a PI calculation based on a deviation between the target yaw rate and the yaw rate detection value;
A main correction coefficient acquisition unit that acquires correction coefficients for the left wheel and the right wheel corresponding to the target rotational speed command values for the left wheel and the right wheel from the output of the calculation unit,
When the output of the calculation unit increases, the main correction coefficient acquisition unit sets one of the correction factors for the left wheel and the right wheel to a constant positive value and decreases the other correction factor. When the output of the calculation unit decreases , the correction coefficient for the left wheel and the right wheel is set to a constant positive value, and one correction coefficient is decreased. Drive torque in the reverse direction is generated with respect to the forward rotation corresponding to the traveling direction in one traveling motor among the traveling motors for the left wheel and the right wheel when the absolute value of the output of the unit is equal to or greater than a predetermined value. Thus, the riding type ground work vehicle characterized by changing the correction coefficient corresponding to one traveling motor from positive to negative. The riding type ground work vehicle according to any one of claims 1 to 6,
The acceleration operator is a pedal that allows input of an acceleration instruction .
A riding type ground working vehicle , wherein the turning operation element is a steering wheel that allows a turning instruction to be input. The riding type ground work vehicle according to any one of claims 1 to 7 ,
The steered wheel is a mechanically steered steerable wheel that is operatively connected to a caster wheel or a turning operator and can be steered in conjunction with the operation of the turning operator. .

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